Prior art designs of such ladder assemblies have already been disclosed as early as 1929 in the U.S. Pat. No. 1,712,942 (Smith). More recent designs are disclosed in EP 527 766, EP 1 402 143, GB 2263932 (Telesteps), WO2004/013445 (Core Distribution), U.S. Pat. No. 5,743,355 (McDonnell), U.S. Pat. No. 5,738,186 (Foxdale), CN 201 273 132 (Zhengjiang Hu), CN 202 194 553 (Xiaoqiu Shen), U.S. Pat. No. 5,738,186 (Jones), DE 20 2012 104992 (Xhen Xiaoling) and DE 20 2012 100131 (Ying Fengruo).
The prior art designs have details that are not satisfactory, either with regard to their construction and/or their practical use. Therefore the present invention aims to propose measures that allow for improvements. These measures can either be applied alone or in combination.